For most urban residents, the unpleasant whiff of a passing garbage truck is part and parcel of city living. But visitors to Songdo International Business District in South Korea will quickly notice that there are no waste collection vehicles plying the streets. This is because the smart city — a 600-hectare expanse of urban area built from scratch on reclaimed land as a private real estate development project — has a waste collection system using pneumatic tubes. Any trash that is thrown into a bin at home or on the street is transported directly to a central sorting and disposal facility, where it is recycled or incinerated.